Micro-Tube Parallel Flow Condenser

[Dindu Nuffin]

I've not seen anyone with electric fans as pleased on the trail as the were with the mdded OEM clutch fan.

I think a huge part of that is that they always put the fans directly on the core without any shroud, rather than stand them back a few inches and with a shroud. When a fan is directly against a heat exchanger, it will only pull (or push) air though the core that's swept by the blades. The core that's under the hub is a dead spot with no air flow, and since there's no shroud to act as a duct to allow the fan to pull air through more of the core than just the swept area, the effectiveness of the rest of the core is subject to the airflow created by vehicle movement. Additionally, a fan mounted directly to the core is choked considerably. Give it more of the core to pull through, and it'll move more air.

Fun, somewhat related fact: a heat exchanger only needs an inlet 1/4 the area of the core to receive enough airflow... provided that it has at least two times the area for the outlet. Head to your local aerospace museum and take a look at how air is routed through various coolers and turbine engines; it's quite fascinating. I would love to stand my pusher fan off, make it a puller and build a duct to distribute the air it moves across the entire condenser core, but space prevents this.

That all having been said, I'm not willing to experiment with my truck on the back side of the radiator. OEM is proven to work (the other local 80 owners with stock fans I wheel with don't have the issues I have), and that's what I'm going to go with.

 

[Dissent]

Well, I did it. Swapped out the condenser (for the Nissens), the evaporator, expansion valve (TXV) and the drier. Lots of work. I evacuated it for 2 hours and it held vacuum just fine. I added 23oz of Freon (20oz liquid then 3oz gas). Ambient was 105F. It did pretty well, at 1500RPM with the doors open, vent temp was about 62F. Lots of bubbles in the site glass. I decided to up it an oz at a time and ended up at the OEM spec of 30oz before noticing any degraded temps at the vents. Right now, at 105A, it's about 54F at the vents @ 1500 RPM but it drops to 44F on the freeway. Idle was about 60F but I had a lot of heat soak, my garage ambient was 115F. I'll drive it to work and let it bake in the sun before reassessing. Having a scale was a really a sanity saver compared to charging the Dodge. I knew exactly how many oz I put in. Well worth the $85. Not sure why 23oz didn't work for me.

I changed out my 100 series fan for my 12" 24v SPAL that I've had on the shelf for 3+ years and it fits great. I'm not sure if it's sufficient to keep up with the Phoenix heat given that it runs at 50% speed. I'll find out tomorrow. It does effectively cover the entire passenger side of the condenser. Worst case, I'll just buy a 12v SPAL and pop it in now that I have the mount points established. I did have to lube the rubber cones on the Nissens with some white lithium grease, they popped right in the cross-member holes. I also had to manipulate each inlet/outlet block a bit to get them to mate properly. No biggie. My evaporator was surprisingly free of debris, I replaced it anyway. I also put 2" foam all around the condenser so the fans have to blow through it. Seems to work fine.

I'll post up install pics tomorrow.

 

[Pacer]

Well, I did it. Swapped out the condenser (for the Nissens), the evaporator, expansion valve (TXV) and the drier. Lots of work. I evacuated it for 2 hours and it held vacuum just fine. I added 23oz of Freon (20oz liquid then 3oz gas). Ambient was 105F. It did pretty well, at 1500RPM with the doors open, vent temp was about 62F. Lots of bubbles in the site glass. I decided to up it an oz at a time and ended up at the OEM spec of 30oz before noticing any degraded temps at the vents. Right now, at 105A, it's about 54F at the vents @ 1500 RPM but it drops to 44F on the freeway. Idle was about 60F but I had a lot of heat soak, my garage ambient was 115F. I'll drive it to work and let it bake in the sun before reassessing. Having a scale was a really a sanity saver compared to charging the Dodge. I knew exactly how many oz I put in. Well worth the $85. Not sure why 23oz didn't work for me.

I changed out my 100 series fan for my 12" 24v SPAL that I've had on the shelf for 3+ years and it fits great. I'm not sure if it's sufficient to keep up with the Phoenix heat given that it runs at 50% speed. I'll find out tomorrow. It does effectively cover the entire passenger side of the condenser. Worst case, I'll just buy a 12v SPAL and pop it in now that I have the mount points established. I did have to lube the rubber cones on the Nissens with some white lithium grease, they popped right in the cross-member holes. I also had to manipulate each inlet/outlet block a bit to get them to mate properly. No biggie. My condenser was surprising free of debris, I replaced it anyway. I also put 2" foam all around the condenser so the fans have to blow through it. Seems to work fine.

I'll post up install pics tomorrow.

Yes, high time, and good results so far!

 

[smritte]

Some years ago I did some experimenting with fans, shrouds, blade pitch and blade count. Both electric and clutch type, worked the best, shrouded with the fan set back a bit. I never found an electric fan that could pull as well as a mechanical. I did find, In most situations the electric pulled enough to keep the engine happy. I don't remember the horse power numbers but I was going to the electric for the efficiency.
My final conclusion was on a single speed fan, the temp would drop, fan shuts off, temp goes up fan comes on. (cycling). Temp wasn't consistent. Two speed fan was better but the low speed was on almost all the time. This is how the factory does it after about mid 90's. Mechanical would vary the output keeping the engine temp consistent and go into a "free wheel" drawing no power when it wasn't needed.

Result was mechanical kept the temp more consistent (fuel management was happier) but could draw more power to run. Electric fan would be better if you could get the flow numbers to where you needed, run a pulse controller to keep the temp consistent and have a tie in to a high pressure sensor on the ac line.

Ended up with a mech fan combo that would pull small animals out of the trees when it engaged fully and a pusher fan tied to the ac compressor (which wasn't needed most of the time). I never tied the ac high pressure into the pusher fan, that would have made the system rock.

Scott

 

[Dissent]

Forgot to mention that I wired in the 2x new leads for the AC cutoff switch. One lead is grounded, the other lead will replace the ground lead on my aux fan relay. This will allow the fan to cycle with the AC. I want to ensure the fan is capable enough first so I'm still running it manually. Adding the 2x leads was a piece of cake.

 

[Dindu Nuffin]

@Dissent interesting about the amount of refrigrant you used. I haven't looked for bubbles in mine, but will this afternoon because you have me wondering I'd they put enough in. Congrats about your results, though!

 

[flintknapper]

Forgot to mention that I wired in the 2x new leads for the AC cutoff switch. One lead is grounded, the other lead will replace the ground lead on my aux fan relay. This will allow the fan to cycle with the AC. I want to ensure the fan is capable enough first so I'm still running it manually. Adding the 2x leads was a piece of cake.

If you added leads to your trinary switch and plan to wire it for automatic operation then yes...the fan will 'cycle' with the compressor but also come on anytime the high side pressure reaches about 220-225 psi. It will also 'run on' for a brief period of time after system shut down until the equalization pressure reaches the cut out minimum. That is how I have mine wired.

 

[Dissent]

If you added leads to your trinary switch and plan to wire it for automatic operation then yes...the fan will 'cycle' with the compressor but also come on anytime the high side pressure reaches about 220-225 psi. It will also 'run on' for a brief period of time after system shut down until the equalization pressure reaches the cut out minimum. That is how I have mine wired.

View attachment 1773245

Yes, thanks for clarifying. This is what I did and what I expect once I get the relay connected.

 

[Bambusiero]

Some years ago I did some experimenting with fans, shrouds, blade pitch and blade count. Both electric and clutch type, worked the best, shrouded with the fan set back a bit. I never found an electric fan that could pull as well as a mechanical. I did find, In most situations the electric pulled enough to keep the engine happy. I don't remember the horse power numbers but I was going to the electric for the efficiency.
My final conclusion was on a single speed fan, the temp would drop, fan shuts off, temp goes up fan comes on. (cycling). Temp wasn't consistent. Two speed fan was better but the low speed was on almost all the time. This is how the factory does it after about mid 90's. Mechanical would vary the output keeping the engine temp consistent and go into a "free wheel" drawing no power when it wasn't needed.

Result was mechanical kept the temp more consistent (fuel management was happier) but could draw more power to run. Electric fan would be better if you could get the flow numbers to where you needed, run a pulse controller to keep the temp consistent and have a tie in to a high pressure sensor on the ac line.

Ended up with a mech fan combo that would pull small animals out of the trees when it engaged fully and a pusher fan tied to the ac compressor (which wasn't needed most of the time). I never tied the ac high pressure into the pusher fan, that would have made the system rock.

Scott

This all makes really good sense to me - nice summary.

Have been looking closely at my stable of cars (other than the Landcruiser).
'99 Lexus GS300 and '07 Subaru Forrester both have similar electric fan setups.
- Dual puller electrics.
- Motors on both fans look the same (still might have internal differences, but manufacturing is motivated to re-use same motor)
- #1 is lower pitch with more blades = lower flow.
- #2 is high angle blade pitch, with fewer blades = higher flow.
- Control system can achieve 4 levels of cooling, still staying with simple relay on/off switching (I think so, not sure).
Level 1 - #1 and #2 wired in series - low flow through entire radiator - maybe the minimum for AC on regardless of anything else.
Level 2 - #1 at full power - medium flow through one side of radiator.
Level 3 - #2 at full power - high flow through one side of radiator.
Level 4 - #1 and #2 at full power - medium / high flow through entire radiator

Multiple high power electric pullers with fully modulated (chop/inverter) closed loop control would really have it all.

 

[Bambusiero]

Fun, somewhat related fact: a heat exchanger only needs an inlet 1/4 the area of the core to receive enough airflow... provided that it has at least two times the area for the outlet. Head to your local aerospace museum and take a look at how air is routed through various coolers and turbine engines; it's quite fascinating. I would love to stand my pusher fan off, make it a puller and build a duct to distribute the air it moves across the entire condenser core, but space prevents this.

Agreed - fascinating stuff. If you have an eye for it it's everywhere.
That 1/4 & x2 area thing might have to do with slowing down the high velocity air (at airplane speed) to recover pressure to push it through the heat exchanger.
If done correctly, velocity and pressure in a fluid stream can be traded back and forth as a constant product.
Would not expect it to be so distinct at automotive speeds, but still there some. But usually ignored.

 

[Dissent]

Here's some pics from my install. Part 1.

Dirty Evaporator

Removed the top radiator support cross beam

Removed the passenger and driver refrigerant block bolt and separated the block. Had to gently pry these (where the bolt goes through) with a small flat blade as I couldn't just pull them apart.

Passenger

Driver

 

[Dissent]

Here's some more pics from my install. Part 2.

Lifted the old condenser straight up to remove

Closeup of the frame cross member holes where the condenser rests and locks into on the bottom. Same on both sides.

Old and New Condensers. It's hard to see in this pic but all brackets are represented on the new Nissens condenser.

 

[Dissent]

Here's some more pics from my install. Part 3.

The only issue was that the left bracket on the OEM Denso unit had a welded nut. The Nissens just has a hole. This proved to be a slight issue mounting my SPAL fan but it was workable.

Nissens missing welded nut on bracket

The Nissens unit in place. Just had to lube up the rubber feet with some White Lithium grease to fit both mounting holes in the cross member. It's tight but slipped right in.

 

[Dissent]

Here's some more pics from my install. Part 4.

I installed new o-rings and lubed them up with Nylog. Installed the bolts and torqued to spec. Off the top of my head it was either 4 or 10 ft. lbs. Just snug.

Passenger side

Driver's side

Then I crammed 2x bags of this 2" insulation around the perimeter and between the condenser and radiator to force airflow through, rather than around, the condenser. Thanks @-Spike- for this tip.

Bottom

 

[Dissent]

Here's some more pics from my install. Part 5.

View of the bottom from above

Sides and top foam. The bottom was under the condenser, the sides and top were between the condenser and radiator.

Top view of the top foam.

Reinstalled the top beam of the radiator support. All done!

 

[smritte]

OK
I feel stupid here. I just skimmed this whole thread and cant find the part number for the nissen condenser. Ill be pulling my motor in a couple of weeks so I may as well get that installed with the new motor and plan my rear ac routing.

Scott

 

[smritte]

@Dissent
By the way, that trans cooler looks a bit out of place in front of that nice shiny condenser.

 

[Dissent]

LOL, it's on Page 7. I just stuck it on the first page as well to save the trouble of searching for it!

 

[Dissent]

@Dissent
By the way, that trans cooler looks a bit out of place in front of that nice shiny condenser.

I know, it was tempting to either paint the condenser or cleanup that trans cooler but once the grill is back on, everyone is simply mesmerized by the chrome "L" and doesn't look any further.

 

[flintknapper]

OK
I feel stupid here. I just skimmed this whole thread and cant find the part number for the nissen condenser. Ill be pulling my motor in a couple of weeks so I may as well get that installed with the new motor and plan my rear ac routing.

Scott